Boxing legend Muhammad Ali has been awarded America's highest civilian honour by President George Bush.

The president drew laughs by assuming a mock boxing posture while presenting the former heavyweight champion with the Presidential Medal of Freedom.

Mr Bush called Ali the "greatest of all time", in a ceremony at the White House at which 13 others were also honoured.

Among them were US Federal Reserve chairman Alan Greenspan, singer Aretha Franklin and golfer Jack Nicklaus.

The ceremony was the first public appearance for Ali, who has Parkinson's disease, in several months.

Placing the medal round his neck, Mr Bush described the 63-year-old as a fierce fighter, a man of peace and the greatest boxer of all time.

Ali gestured to Mr Bush that he would be mad to take him on

"As Muhammad Ali once said, 'It's not bragging if you can back it up.' And this man backed it up," the president said.

"Across the world, billions of people know Muhammad Ali as a brave, compassionate and charming man."

The boxer responded to Mr Bush's mock punch by twirling a finger at his head, a gesture indicating the president would be crazy to take him on.

Ali dominated boxing in the 1960s and 70s but was stripped of his heavyweight title in 1967 for refusing to fight in the Vietnam War. He later won back his title after his conviction was overturned on appeal.

Mr Greenspan's award comes ahead of his retirement next January after 18 years in charge of the US Federal Reserve.

2005 MEDAL RECIPIENTS

Muhammad Ali

Carol Burnett

Vinton Cerf and Robert Kahn

Robert Conquest

Aretha Franklin

Alan Greenspan

Andy Griffith

Paul Harvey

Sonny Montgomery

General Richard B Myers

Jack Nicklaus

Frank Robinson

Paul Rusesabagina

His era was known for "phenomenal economic growth, high productivity, and unprecedented innovation and opportunity for all our citizens", Mr Bush said.

Other medal recipients included internet pioneers Vint Cerf and Bob Kahn, who co-created the basic networking protocol that keeps the net running to this day.

The president praised Aretha Franklin as "still the best singer in the world, bar none".

The medal is generally given to those who have made exceptional contributions to America's security or world peace, or have had a significant impact on the nation's cultural life.

US President Harry Truman established the medal in 1945 and it was initially intended to recognise significant civilian contributions to the war effort. It was revived in 1963 by John F Kennedy as a reward for distinguished service to the American nation.